swarm: export ipfs_p2p_peers_total metric

License: MIT
Signed-off-by: Lars Gierth <larsg@systemli.org>

p2p/net/swarm/swarm.go

@@ -19,6 +19,7 @@ import (
 	ps "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-peerstream"
 	pst "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-peerstream/transport"
 	psy "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-peerstream/transport/yamux"
+	prom "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus"
 	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 )
 
@@ -26,6 +27,13 @@ var log = eventlog.Logger("swarm2")
 
 var PSTransport pst.Transport
 
+var peersTotal = prom.NewGaugeVec(prom.GaugeOpts{
+	Namespace: "ipfs",
+	Subsystem: "p2p",
+	Name:      "peers_total",
+	Help:      "Number of connected peers",
+}, []string{"peer_id"})
+
 func init() {
 	tpt := *psy.DefaultTransport
 	tpt.MaxStreamWindowSize = 512 * 1024
@@ -82,6 +90,10 @@ func NewSwarm(ctx context.Context, listenAddrs []ma.Multiaddr,
 	s.cg.SetTeardown(s.teardown)
 	s.SetConnHandler(nil) // make sure to setup our own conn handler.
 
+	// setup swarm metrics
+	prom.MustRegisterOrGet(peersTotal)
+	s.Notify((*metricsNotifiee)(s))
+
 	return s, s.listen(listenAddrs)
 }
 
@@ -273,3 +285,22 @@ func (n *ps2netNotifee) OpenedStream(s *ps.Stream) {
 func (n *ps2netNotifee) ClosedStream(s *ps.Stream) {
 	n.not.ClosedStream(n.net, inet.Stream((*Stream)(s)))
 }
+
+type metricsNotifiee Swarm
+
+func (nn *metricsNotifiee) Connected(n inet.Network, v inet.Conn) {
+	peersTotalGauge(n.LocalPeer()).Inc()
+}
+
+func (nn *metricsNotifiee) Disconnected(n inet.Network, v inet.Conn) {
+	peersTotalGauge(n.LocalPeer()).Dec()
+}
+
+func (nn *metricsNotifiee) OpenedStream(n inet.Network, v inet.Stream) {}
+func (nn *metricsNotifiee) ClosedStream(n inet.Network, v inet.Stream) {}
+func (nn *metricsNotifiee) Listen(n inet.Network, a ma.Multiaddr)      {}
+func (nn *metricsNotifiee) ListenClose(n inet.Network, a ma.Multiaddr) {}
+
+func peersTotalGauge(id peer.ID) prom.Gauge {
+	return peersTotal.With(prom.Labels{"peer_id": id.Pretty()})
+}